The W50 supernova remnant – now known as the Manatee Nebula – seen at radio wavelengths (green) against the background of stars and dust (seen at infrared wavelengths).

Supernova remnant cloud imaged by VLA radio telescope system

The cloud closely resembles the endangered Florida manatee

Manatees are gentle giants, until black holes, which are far from gentle

A NEW VIEW of a 20,000-year-old supernova remnant and shows how this giant cloud resembles a beloved endangered species, the Florida Manatee.

Known as W50, the supernova remnants is one of the largest ever viewed by the US National Science Foundation’s (NSF) Karl G. Jansky Very Large Array (VLA), which has recently been upgraded. Nearly 700 light-years across, seen from Earth W50 covers two degrees on the sky – that’s as wide as four full Moons.

The enormous W50cloud formed when a giant star, 18,000 light-years away, exploded as a supernova around twenty thousand years ago, sending its outer gases flying outward in an expanding bubble.

The remaining, gravitationally-crushed relic of that giant star, most likely a black hole, feeds on gas from a very close, companion star. The cannibalised gas collects in a swirling cloud around the black hole.

The black hole’s powerful magnetic field snags charged particles out of the cloud and channels them outward in powerful jets travelling at nearly the speed of light.

The system shines brightly in both radio waves and X-rays and is known collectively as the SS 433 microquasar.

Over time, the microquasar’s jets have forced their way through the expanding gases of the W50 bubble, eventually punching bulges outward on either side. The jets also wobble, like an unstable spinning top, and blaze vivid corkscrew patterns across the inflating bulges.

A Florida manatee rests underwater in Three Sisters Springs in Crystal River, Florida.

New namesake

When the W50 image reached the NRAO director’s office, Heidi Winter, the director’s executive assistant, saw the likeness to a manatee, the endangered marine mammals known as ‘sea cows’ that congregate in warm waters in the south-eastern United States.

Florida manatees are gentle giants that average around three metres long, weigh over 500kg, and spend up to eight hours a day grazing on sea plants. They occupy the remainder of their day resting, often on their backs with their flippers crossed over their large bellies, in a pose closely resembling W50.

Dangerous encounters with boat propellers injure many of these curious herbivores, giving them deep, curved scars similar in appearance to the arcs made by the powerful jets on the large W50 remnant.

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